1. Field of the Invention
The present invention relates to an ion neutralizer. More particularly, the present invention relates to a neutralizer which neutralizes electric charge efficiently and produces a fast atom beam in an ultra-high vacuum.
2. Prior Art
An ion neutralizer which neutralizes electric charge on ions and produces a fast atom beam in an ultra-high vacuum is known.
FIG. 5 is a schematic view showing one example of conventional gas cell type ion neutralizers.
In the figure, reference numeral 1 denotes an ion source, 2 an ion beam, 3 a gas cell, 4 a gas nozzle, 5 a reaction gas, 6 a fast atom beam, 7 a vacuum container, 8 a vacuum pump, 9 an ion beam entrance hole 9, and 10 a fast atom beam exit hole.
The ion source 1, the gas cell 3 and the gas nozzle 4 are accommodated in the vacuum container 7.
The ion neutralizer comprising the above-described constituent elements operates as follows. After the vacuum container 7 has been sufficiently evacuated by the vacuum pump 8, an ion beam 2 is emitted from the ion source 1 toward the gas cell 3. A reaction gas 5, e.g., argon, has previously been injected into the gas cell 3 from the outside through the gas nozzle 4. The ion beam 2 entering the gas cell 3 through the ion beam entrance hole 9 collides with the molecules of the argon gas 5, thereby losing its electric charge, and thus being converted into a fast atom beam 6, which is released from the fast atom beam exit hole 10 of the gas cell 3.
However, in the above-described gas cell type ion neutralizer, the argon gas 5 injected into the gas cell 3 flows out from both the ion beam entrance hole 9 and the fast atom beam exit hole 10, causing a rise in the gas pressure in the vacuum container 7, and thus making it difficult to take out the fast atom beam 6 under a high vacuum. In particular, when a large amount of fast atom beam 6 is to be obtained, a large amount of argon gas 5 must be injected into the gas cell 3, so that it becomes more difficult to maintain a high vacuum in the vacuum container 7.
In the prior art, in order to maintain a high vacuum, it is necessary to employ for example, a vacuum pump 8 having an exceedingly large capacity, differential evacuation mechanism, etc. However, such means lead to an increase in the overall size of the apparatus, and an increase in the production and running costs of the apparatus. Thus, conventional ion neutralizers are disadvantageous from an economic point of view.
In the light of the above-described circumstances, it is an object of the present invention to provide an ion neutralizer designed to produce a fast atom beam in an ultra-high vacuum both easily and economically.